docs: def form_invalid(self, post_form, attachment_formset, poll_option_formset, **kwargs):
          """ Processes invalid forms. """
          poll_errors = [k for k in post_form.errors.keys() if k.startswith('poll_')]
          if (
              poll_errors or
              (
                  poll_option_formset and
                  not poll_option_formset.is_valid() and
                  len(post_form.cleaned_data['poll_question'])
              )
          ):
              messages.error(self.request, self.poll_option_formset_general_error_message)
  
          return super().form_invalid(
              post_form, attachment_formset, poll_option_formset=poll_option_formset, **kwargs)